Fluorescence correlation spectroscopy system for analyzing particles in a medium

Abstract

The present invention relates to a fluorescence correlation spectroscopy system (1) for analyzing particles in a medium (2), including a means (3) for detecting the light (7) emitted by the particles in the medium (2), said means (3) being coupled to a waveguide (4), for which purpose the end piece of the guide (4) comprises a means (4b; 5) for confining the light (7) injected into the guide (4).

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This Application is a National Stage Entry of International Application No. PCT / FR2010 / 051762, having an international filing date of Aug. 24, 2010; which claims priority to French Application No. 0955987, filed Sep. 2, 2009; the disclosure of each of which is hereby incorporated in its entirety by reference.TECHNICAL FIELD[0002]The present invention relates to the field of fluorescence correlation spectroscopy systems for detecting and analyzing solution luminescent or optically diffusing molecules, these molecules can be fluorescent under the effect of an exciter light.PRIOR ART[0003]In conventional optically diffusing luminescent molecules detection modes, it is known to use confocal microscopy systems. In the case of analyzing fluorescent particles, these systems comprise a laser source emitting an excitation laser beam, a dichroic mirror, a microscope with a highly enlarging lens and high numerical aperture, an optical conjugation dev...

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Benefits of technology

[0014]Based on a fluorescence correlation spectroscopy system for analyzing particles in a medium, including means for detecting the light emitted by the particles in the medium, this means being coupled to a waveguide, the purpose of the present invention is to make it a system which may exhibit a simplicity and low production cost, constitute a portable spectroscopy probe and offer single-molecule sensitivity.

[0016]This solution makes it possible to enhance the reception of light emitted by the particles, whether this emission is due to the luminescent or the optical diffusing properties of the particles, or their fluorescence under the effect of an exciter light. Thus, it is only possible to observe a small observation volume with the detector in the medium to analyze, thus making it possible to obtain a much lower resolution to that obtained with the spectroscopy systems with the related art waveguides, thus making it possible to resolve down to the dimension of a unique molecule with a high signal to noise ratio.

[0019]Finally, this combination makes it possible to have a portable probe, constituted by the waveguide provided at its end piece with confinement means. This probe may be directly immersed in a solution to be analyzed, the position of the observation volume thus being dependent on the position of the guide end piece. This probe, connected to the rest of the system which may not be portable, offers an ease of use and is perfectly suitable with applications such as endoscopy, based on in situ measurements.

[0037]Preferably, the illumination means is coupled to a waveguide thus making it possible to delocalize the excitation source. This new waveguide may also be provided at its end piece with light confinement means which crosses this guide. The excitation light beam is thus also confined in a small dimension excitation volume. The illumination means is thus arranged such that the excitation volume corresponds to the observation volume. Thus, a perfectly concentrated and localized exciter power is ensured and thereby, is even higher.

Problems solved by technology

Furthermore, the combination of the confinement means and of the waveguide, coupled on the one hand to the detector and on the other hand to the observation volume in the medium to analyze, makes it possible to simplify the system, since the use of a microscope lens and a passive substrate becomes useless.

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